And the LORD said, ‘My Spirit shall not strive with man forever, for he is indeed flesh; yet his days shall be one hundred and twenty years.’
(Genesis 6:3, NKJ)
How are these words of the Lord to be understood? With other Bible readers, I always took this passage to refer to the age of man and not to anything else. That reasoning seemed to make sense, “his days shall be one hundred and twenty years.”
However, Genesis 11 records that the father of Abram, Terah, lived to be 205 years old. And most of those before him (also recorded in Genesis 11) lived more than 120 years. Moses, in contrast, did not live as long as those before him, for Moses died at the age of 120 (Deuteronomy 34:7).
One reasonable explanation for the lapse in time between the greater ages of men in the earlier parts of Genesis (i.e. Noah, Terah, etc.) to the decreasing ages of men (i.e. Moses) shortly after the pronouncement of the Lord in Genesis 6:3 might be that the lowering of the maximum age to 120 years was not immediate. Here, we might reflect on the fall of Adam and Eve in the garden.
The Lord had clearly said, “Of every tree of the garden you may freely eat; but of the tree of the knowledge of good and evil you shall not eat, for in the day that you eat of it you shall surely die” (Genesis 2:16-17). However, neither Adam or Eve physically died immediately, but they were surely in the “state of death.” Also, and especially, to be outside of God’s blessing and favor surely does mean certain eternal death.
I had understood these words of our Lord in Genesis concerning the 120 years to be referring to the limitation of man’s age due to his wickedness. It was a word of judgment. It made sense to me. And even today, you hear of few people living over 110 years, let alone over that. The explanation seemed “to fit.”
Nevertheless, another, and more likely, explanation exists which was recently brought to my attention…
The word of the Lord concerning 120 years is certainly a word of judgment. But it is not to be understood as a word of judgment with reference to man’s age. It is word of judgment with reference to how long the wicked of the world had before the coming destruction of the flood.
Note these following verses in Genesis 6:
“Then the LORD saw that the wickedness of man was great in the earth, and that every intent of the thoughts of his heart was only evil continually. And the LORD was sorry that He had made man on the earth, and He was grieved in His heart. So the LORD said, ‘I will destroy man whom I have created from the face of the earth, both man and beast, creeping thing and birds of the air, for I am sorry that I have made them.’ But Noah found grace in the eyes of the LORD” (Genesis 6:5-8);
“The earth also was corrupt before God, and the earth was filled with violence. So God looked upon the earth, and indeed it was corrupt; for all flesh had corrupted their way on the earth. And God said to Noah, “The end of all flesh has come before Me, for the earth is filled with violence through them; and behold, I will destroy them with the earth” (Genesis 6:11-13).
The world was corrupt. The people were wicked. Judgment was coming…
Genesis 5 records that Noah was 500 years old. Noah and his family (wife, three sons, and three daughters-in-law), totaling eight people, entered the ark when Noah was 600 years old. This leaves a difference of only 100 years, twenty less than the Lord’s, “yet his days shall be one hundred and twenty years.”
In other words, the Lord wasn’t speaking of limiting man’s age, but limiting the amount of time before man’s judgment, that is, giving wicked man time to repent, to change his ways (i.e. Sodom and Gomorrah, Genesis 19:12-14; Jonah & Nineveh, Jonah 3:4).
Such truly is the way of the Lord, the way of grace and mercy, to give time to repent, to give time to turn from sin and believe His word and promises, for the Lord says, “I have no pleasure in the death of the wicked, but that the wicked turn from his way and live” (Ezekiel 33:11).
That time is now, not to wait as those who perished in the flood:
“Scoffers will come in the last days, walking according to their own lusts, and saying, ‘Where is the promise of His coming? For since the fathers fell asleep, all things continue as they were from the beginning of creation.’ For this they willfully forget: that by the word of God the heavens were of old, and the earth standing out of water and in the water, by which the world that then existed perished, being flooded with water. But the heavens and the earth which are now preserved by the same word, are reserved for fire until the day of judgment and perdition of ungodly men. But, beloved, do not forget this one thing, that with the Lord one day is as a thousand years, and a thousand years as one day. The Lord is not slack concerning His promise, as some count slackness, but is longsuffering toward us, not willing that any should perish but that all should come to repentance” (2 Peter 3:3-9).
Thus does our Lord say through the St. Paul the apostle:
“We then, as workers together with Him also plead with you not to receive the grace of God in vain. For He says: “In an acceptable time I have heard you, And in the day of salvation I have helped you.” Behold, now is the accepted time; behold, now is the day of salvation” (2 Corinthians 6:1-2).
That the Lord would reveal the coming destruction of the world by flood as in Genesis (or by fire, 2 Peter 3:10ff) is not foreign to Holy Scripture. That the Lord would reveal such coming destruction by means of giving the amount of time before such an event is also not foreign to the way God works, for the Lord does indeed desire sinners “to be saved and to come to the knowledge of the truth” (2 Timothy 2:4). However, if they do not, judgment is sure to come and will not delay.
 This latter point might be what is truly meant with reference to the Lord’s words, “surely die.” We might immediately think of physical death, but physical death, though indeed a result of sin, is not the instantaneous, nor the ultimate, consequence, but separation from God is, and all that this means.
 In Genesis 19, only Lot, his wife, and two daughters fled the city alive. The sons-in-law refused to depart. As for Nineveh, the king and its citizens did repent and were thus spared, though destruction did come later (Nahum 1:1ff; Zephaniah 2:13)